NATURE 



151 



THURSDAY, DECEMBER 9, 1909. 



PLANT RECORDS OF THE ROCKS. 

 Studies in Fossil Botany. By Dr. Dukinfield H. 

 Scott, F.R.S. Second edition. Vol. I., Pterido- 

 phyta. Pp. xx + 363. Price 6^. net. Vol. II., 

 Spermophyta. Pp. xiii + (355-676). Price 55. net. 

 (London: A. and C. Black, vol. i., 1908; vol. ii., 

 1909.) Price, 2 vols., 10s. 6d. net. 



IN the preface to the first edition the author 

 expressed the hope that the palasontological 

 record "will no longer be ignored by students of the 

 evolution of plants." Since these words were written 

 the study of the plant-records of the rocks has made 

 steady progress, not only as regards results, but in 

 the vigorous growth of interest shown in the relics of 

 past floras. This remarkable activity is in large 

 measure the direct result of the influence exerted by 

 Dr. Scott, not oifly by his own researches and by the 

 encouragement and generous assistance which he is 

 always ready to give to younger workers, but in no 

 small degree by his well-balanced and lucid treatment 

 of that branch of botany to which he has devoted 

 himself with conspicuous success. 



The recent issue of the " Studies " is a new edition 

 in more than name; two volumes replace the single 

 volume in which the lectures were originally pub- 

 lished, and, as the result of the rapid progress of 

 palffiobotanical work during the last eight years, many 

 of the chapters have been largely re-written and others 

 have been amplified. In the section devoted to the 

 Equisetales the additions are few ; reference is made 

 to Mr. Hickling's recent account of the course of the 

 vascular bundles in the sporangiophores of Palaeo- 

 stachya vera, and to Halle's monograph of Mesozoic 

 species of Equisetites. In the first edition a brief 

 reference was made to the important discovery of 

 Lepidocarpon, a seed-bearing lycopodiaceous strobilus : 

 subsequent work by Dr. Scott and others has now 

 rendered possible a more adequate treatment of this 

 and similar types. A drawing of a transverse section 

 of Lepidodendron Wuiischianitm, published in the first 

 edition, is again reproduced with a broad band of 

 tissue labelled "phloem," though it consists of ex- 

 tremely short parenchymatous cells, and a few imma- 

 ture xylem elements. It is a fact of considerable 

 interest that in Lepidodendron stems which have 

 formed a broad cylinder of secondary xylem, no true 

 secondary phloem has been discovered. To the con- 

 sideration of this question Dr. Scott hardly does 

 justice. There are still many points to be cleared up 

 in regard to the morphology of Palasozoic lycopods, 

 and this can be done only by a detailed comparative 

 treatment of all known species, founded on anatomical 

 characters. 



It is, however, especially in the account of the ferns 

 that the results of recent investigations are most 

 apparent. The student of Palaeozoic ferns has now 

 to face the difficulty of distinguishing between true 

 members of the Filicinece and fern-like plants which 

 bore seeds. The account of the Botryopterideae, a 

 group of ferns which has gained considerably in 

 NO. 2093, VOL. 82] 



importance since the removal of many genera of 

 Palaeozoic " ferns " to the new group Pteridospermes, 

 is particularly welcome as coming from one who is 

 exceptionally well qualified to deal with these still 

 imperfectly known types. The excellent description, 

 which is necessarily condensed, leads one to express 

 the hope that Dr. Scott will soon publish a more 

 comprehensive account of his researches into the 

 structure and affinities of these generalised ferns. 

 The account of the genus Lyginodendron has been 

 modified as the result of Dr. Kidston's important con- 

 tribution to our knowledge of the male reproductive 

 organs, which had been previously referred to Zeiller's 

 genus Crossotheca and regarded as fern sporangia. 

 The chapter on the Medulloses contains interesting 

 new matter, including some admirable drawings by 

 Mr. Maslen of the seed Trigonocarpon and photo- 

 micrographs illustrating Prof. Oliver's recent work on 

 the multicellular pollen-grains, and what are believed 

 to be the remains of motile male gametes of 

 Stephanospermum. 



A word of praise is due to the publishers for the 

 quality of the type and for the successful reproduction 

 of the illustrations. Some new figures have been 

 added, the most striking of which is, perhaps, a 

 drawing of a transverse section of a young vascular 

 bundle of Botryopteris hirsuta, showing the thin- 

 walled immature xylem, with a few lignified proto- 

 xylem elements. It is no exaggeration to say that 

 the volumes before us afford the most convincing 

 demonstration so far presented in book-form of the 

 possibilities of palaeobotanical research. As we read 

 the descriptions of many of the extinct types, and note 

 the perfection of the preservation of their tissues, we 

 forget that the material from which the data have 

 been obtained has for countless ages been entombed in 

 the older rocks of the earth's crust. 



Though mainly concerned with Palaeozoic plants. 

 Dr. Scott adds a chapter on Mesozoic gymnosperms, 

 in which special attention is directed to Mr. Wieland's 

 able monograph of the remarkable silicified cycadean 

 stems from America. In the clearly written account 

 of these plants, emphasis is laid on the striking 

 differences between their flowers and those of recenr 

 cycads, a difference which is necessarily somewhat 

 obscured by the apphcation of the term cycad to 

 plants the reproductive organs of which differ toto 

 coclo from those of the CycadaceEe. The opinion held 

 by several botanists that the results of Mr. Wieland's 

 work afford a clue to the solution of the problem of 

 the origin of the angiosperms receives due attention. 

 Bearing in mind the scope of the " Studies," it would. 

 be unreasonable to find fault with the brevity of the 

 section devoted to the past history of the Coniferales. 

 In the admirable chapter devoted to general results,, 

 the author adopts a new grouping of the vascular 

 plants, which he naturally speaks of as provisional. 

 As knowledge increases, we conveniently record pro- 

 gress towards what we believe to be a closer approxi- 

 mation to a natural scheme of classification by means 

 of changes in the arrangement of the subdivisions or 

 by a redistribution of genera. Any change challenges 

 criticism, but, whether accepted or not, it stimu- 

 lates discussion and helps us to correlate our 



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